The main benefit is SEO helps increase visibility of the website. Always people makes website to increase his business online and here seo will help. As per my opinion, this is a big benefit of SEO.

Two types of SEO are over there.
1.On page 2.Off Page
On page is about to improving meta content.Off page is about to social sharing,Link building etc.

search engine optimization is the process of optimizing the website on any search engine so that it can rank above on search engine result page (SERP).

Search Engine Optimization is used to improve the visibility of the website in search engine. It uses various techniques to increase traffic on the website,in creating quality backlinks etc.

it is a process of optimizing the website and it is helpful for increasing website ranking.

Search engine optimization (SEO) is an area of website development that seeks to improve the way content is ranked by search engines in organic search results.
Benifits of SEO are:
1.Increased Traffic
2. Cost effectiveness
3. Increased site usability
4. Brand Awareness

SEO Is Important for your Business because it increases visibility of your product or services in search engine result page.

While the benefits of SEO are vast, here are the top 5. ... SEO also focuses on creating informative and keyword relevant title tags and meta descriptions, which show up in the result pages. Having optimized tags and descriptions helps to increase click through rate, which also promotes increases in qualified web traffic